Easy, safe, effective and DIY treatment of rust on your vehicle. Just happens to be cheap too.Very popular with the vintage auto restorers. Even though they can afford more expensive products, many say this is the best:

Penetrol Paint Conditioner

Started as a paint conditioner, but they sold so much to the car restoration customers that they changed the labeling to say it also treats rust.I get my from Lowe's for under $10 a can. Use it like paint.

PrepApplies on clean dry steel, be it new, old or rusted. You should remove rust scale first, as it can continue rusting under the scale if you don't. You can leave the surface rust; Penetrol soaks in and seals against oxygen and water vapour, and bonds with trapped oxygen. Some use it on aluminum – I haven't, don't know how that works. Special de-greasing products are not required. Cleaning with a pressure washer first is popular. Hand washing with dishwashing detergent is also popular. Reports of a wide range of prep work, even none, used with success. Just make sure the metal is dry before you apply the Penetrol.

ApplicationApply with brush, roller, paint sprayer or undercoating sprayer. For small jobs, a cheap dollar store cleaner/water sprayer works well for getting it up and into hard to reach places, like inside channels, but uses around 3x more Penetrol than necessary.

Top CoatOnce the Penetrol has dried, it needs additional time to cure; leave it a week to be sure.Leave it as is (it doesn't need a topcoat), or apply your choice of paint if you want a colour. Your choice of undercoating, or you can touch-up the Penetrol coat once a year.

Very practical for vehicles, especially daily drivers. Apply one year. After that, inspect each year. Wherever it is missing (either got scraped off, or paint, undercoating or other material has fallen off) and you've got metal showing, it can be touched up with Penetrol.

Personal ExperienceWhere I can get down to rust-free steel (new metal, new parts or rust removed with Evapo-Rust), I do the poor-man's powder coat. I paint with duplicolor engine enamel, then bake in the oven or heated with a propane torch. Then apply undercoating (we salt roads in winter here) to protect anywhere it gets scraped (undercoating I use creeps). Touch up undercoating once a year.

Where I can't get all the rust off, I use the Penetrol. Dry. Cure. Second coat. Dry. Cure. Apply undercoating.

Against the recommendation, I've used it on light rust scale after brushing for lose scale, leaving whatever dirt stays on (soaks through it), and had excellent results. Only sometimes requiring a second coat where a spec of rust pokes through after some months. I've also applied it over multi-decade old dried out hard undercoating that had cracks in it, after knocking off what came off easily. Works great, coating the newly bare metal and soaking in under the edges and cracks. We salt the roads here in winter. So far, no rust creep under the coating anywhere I've used it. Appears to soak into ferrous oxide, but only coats ferric oxide. But these are not formal tests, just judgement by eye. I've subsequently removed deeper scale where I was testing, and found the Penetrol had soaked in through available cracks, but of course only where the expanded ferrous oxide had opened a defect between ferrous oxide and ferric oxide or good metal.

Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

POR-15 is an expensive product. Difficult to use. Short shelf life once opened. Very poor performance. When I got mine, its marketing material stated that you don't have to prep surfaces by degreasing. The fine print specified degreasing required. I consider that deceptive.

First-hand Personal Experience (yes, that formal): Even following the exact prep specified, every application I've done with POR-15 on steel has failed, usually within the same year. Rusting and breaking through the POR-15, or rust creeps under it. For treating rust and when used to treat brand new steel. And it frequently peels off (even when not in UV and when topcoated). Difficult to work with. Wear gloves!!! Will often discolour in UV; needs a protective topcoat. Peels very quickly if not protected by topcoat.

Used the silver POR-15 to coat the outside of an aluminum carb I refurbished. Fully cleaned and degreased, POR-15 applied with a bristle brush skinned down with good flow, looked great and didn't fail. Still looked "brand new" when the car was junked.

Did work well as a body filler when mixed with polyester spheres (the kind used to make a wing-surfacing dry-slurry with epoxy resin for fiberglass wings), but really hard to sand. Didn't discolour in UV... One of the places I used it the resulting filler cracked, and the metal under rusted. But this is not its recommended use. I had it and was trying to find something useful to do with it.

I do NOT recommend POR-15 for rusted or new steel. I recommend you stay clear of it. Waste of money. Except for the one success I had with it on aluminum.

Rarely have I tried a product that so utterly failed at its claims. And I persisted for two years trying to make it work, with all of the wonderful reviews. I had several cans of it, some open, some brand new. I gave it away to people who didn't believe me and wanted to try it. They threw it out after trying it. The guy who took the time to do the whole underside of his Yukon (I had a lot, for restoration work) was really pissed that he wasted so much time, and that the Yukon wasn't protected and rusted. I kept two tiny cans to use on aluminum parts.

They do sell a very very good degreaser. A true degreaser, not a solvent that dilutes grease and spreads it around. Very expensive, but easy to use and works the best I've used - highly recommend it.

Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

Without bothering to investigate.... This is almost certainly simply good old fashioned Phosphoric Acid, which mechanically minded people have used on rust for ages -- to the amazement of "normal" people. I learned about it from an old motorcycle restorer 40 years ago. The best know variety is thick and sticky and known as Naval Jelly -- for treating boats. I have a thin liquid version here with the brand name Ospho, from the local Ace Hardware store. Costs little and works well, but hardly magic. Every few years a new brand name is launched with much hoopla and high prices. Just go to any hardware or paint store and ask for phosphoric acid treatment. Now you too will be one of the Inner Circle Of Metal Magicians.

Elliot wrote:I have a thin liquid version here with the brand name Ospho,

I've been pleased with Ospho. It not only makes light rust paintable (e.g. after sanding and cleaning, Ospho will turn the light and invisible rust to iron phosphate [right?]) but you also leave it in place and primer over it. That is, rub on some Ospho, let dry, and start painting. I think Naval Jelly needs to be removed somehow.

Hmmmm... indeed. I stand corrected; not phosphoric acid. Thanks for investigating. Lots of Naphta, which is similar to gasoline. Some Stoddard Solvent (mineral spirits) which is essentially Kerosene -- which is the main component in WD-40. So... Petroleum solvents, and oils -- reminiscent of WD-40. Or am I on the wrong track all over again? I'm definitely stretching my understanding of chemistry. I'm looking forward to learning more. With the Playa dust causing so much rust on our toys, this is definitely a worthwhile discussion.

Elliot wrote:Without bothering to investigate.... This is almost certainly simply good old fashioned Phosphoric Acid,...

Nope. Penetrol isn't that.It's not a rust remover. Use it as a rust treatment paint. Think of it as Tremclad rust treatment paint, only it works, and lasts. Negative is you have to give it cure time before you topcoat, if you want a topcoat. Well, not quite like Tremclad; no colour and I haven't tried adding a pigment to it. No need. Easily top coated.

But I used to use phosphoric acid based rust removers. Now I use evapo-rust. Even reconditioned suspension springs with it. Horribly expensive, but works well. But I find it often takes more time that their directions say.

Elliot wrote:Hmmmm... indeed. ... -- reminiscent of WD-40. Or am I on the wrong track all over again? ...

Good guess, but thankfully nothing like WD-40.This dries to a hard finish, like linseed oil and tun oil and other "drying oils" correctly applied to wood. Pre-polymerized means you're not waiting weeks for a cure.

Yup.Made with drying oils.They dry by the solvent evaporating. Then they cure by bonding with oxygen. In between the two, you have a period where they can polymerize. After the solvent is gone, the coat is obviously thinner on the applied surface. But, as it's largely a drying oil, as it polymerizes, it also shrinks/skins-down into a thinner coat. Think skin-tight.

The great part is that the polymers of linseed oil link together (and possibly cross-link), then they cure by bonding with oxygen into polymers of linoxyn. So when applied to rust, it coats and soaks in, then cures. The O2 bonding removes O2 under the coating from being available for rusting. As neither oxygen or water vapour can get under the coating, further rusting is limited to what oxygen is in the metal - in practical terms, naught. I suspect the oils also absorb and encase salts that may be mechanically present in the oxides, thereby removing them from being available from promoting rust. Same for any dirt you didn't get off: Penetrol soaks through and encases it, so it can't absorb water (which can hold O2 and salts) and hold it next to the metal - recommended method is to remove dirt first, but...

Some day I'm going to try it as a replacement for my various pure oil & blends based on tung oil or linseed oil for my wood projects. But what I have works very well, so I have to wait for a project that doesn't matter much. Would sure be less expensive than the fancy "pure" products that I'm using now for wood projects.

Last edited by Canoe on Fri Feb 24, 2012 10:29 am, edited 1 time in total.

Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

Canoe wrote:...Where I can get down to rust-free steel (new metal, new parts or rust removed with Evapo-Rust), I do the poor-man's powder coat. I paint with duplicolor engine enamel, then bake in the oven or heated with a propane torch...

Here's an example of that method:

rusted but dry;

soaked in evapo-rust to treat rust, tap water rinsed, dried, wiped;

engine enamel, baked.

(before use, I apply an undercoating topcoat - not in photo)It also does an amazing job on rusted bolts and nuts.

p.s. Very Important. If you're married, do the baking outdoors in the BBQ, not in the kitchen oven. Ignore this at your own peril. If you're single, very brave, or stupid, you can bake in the the kitchen oven, on a cookie sheet to buffer the heat from the element, with the part(s) sitting on parchment paper NOT wax paper. Get temperature and time from the directions on the can. At the recommended temperatures, the heat will not change the temper of the steel.

front springs - top view.jpg

You do not have the required permissions to view the files attached to this post.

Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

Canoe wrote:... Used the silver POR-15 to coat the outside of an aluminum carb I refurbished. Fully cleaned and degreased, POR-15 applied with a bristle brush skinned down with good flow, looked great and didn't fail. Still looked "brand new" when the car was junked...

If you use POR-15 for a carb, depending on the surfaces you coat, you may no longer have a path to ground for the heating element for the choke control. You have to provide a grounding wire.

Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

EspressoDude wrote:on steel, naval jelly scrubbed on with a brass bristle brush imparts a slight brass look to the steel

Now that's cool! A DIY surface alloy.Like using silvo on brass.

Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

Elliot wrote:...With the Playa dust causing so much rust on our toys, this is definitely a worthwhile discussion.

If you stay there.We get it on toys' surface, in seams and cracks, then bring it home where it does its work. If we bring it to more moisture, it does it faster. Some bicycles are trashed in a single burn (more exposed metal than a car or truck).

CIMG0497-713385 sm.jpg

You do not have the required permissions to view the files attached to this post.

Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

My experience with por-15 does not mirror yours. I have done several rotisserie restorations on old chevys (current project is a 53 Buick Skylark convertible), and have had decent results. But on steel I would blast and powdercoat, so there was no need for the any other treatment. On the body, I would remove all rusted parts and panels, and weld in new. Wurth makes a great undercoat, and you may want to suggest that to your friend for his Yukon.

As for rust removal, the best method I have found for small parts is to mix a solution of oxalic acid and water. Let them soak for a day or two and the rust will be gone. This is especially useful on small chrome plated parts that have rust and mild pitting.

The POR-15 was a huge disappointment. The way it wets on was encouraging. The way it rusted underneath, rust creeped or peeled off was a pain. Where it peeled off in sheets, it did leave the metal clean and ready for something else (if you got to it right away), except for the rust creep or spots. Our winters here have a lot of thermal cycling above/below freezing, and wet, and road salt, but it's supposed to handle that.

Wish I could powder coat. But I don't have the facilities and it's horribly expensive to get it done here. The engine enamel and baking or torch seems to work well. Two support rods I had sandblasted (before finding the evapo-rust) had the engine enamel skin down to show the sandblasting texture. Taping the two together compressed the texture flat where they impacted, but the paint followed and stayed on, suggesting it would be good for taking stone chips without exposing anything that can rust. Unfortunately, I didn't practically test that as I undercoated (see below) the parts prior to assembly and that undercoating keeps the part coated, hence protected.

I'll try the oxalic acid next time round. The evapo-rust works great, but is expensive. If you get a larger part that's too thin to sandblast or even wisk, or you don't want any surface texture change, you can place paper towels on the part and soak it with evapo-rust, then place the part into a large garbage bag to prevent the water in the evapo-rust evaporating, or cover with a plastic wrap and tape the edges. Takes a long time if outdoors in cooler temperatures. Not having enough evapo-rust to immerse the suspension springs, I put one one in a heavy duty plastic garbage bag, placing that in the bottom of a plastic tub, putting evapo-rust in the bag, then filling the tub with hot water. The hot water displaces the garbage bag so it holds the evapo-rust next to the spring. The hot water speeds the rust removal. Took better part of two days per spring, even with hot water refreshed from time to time, but only rust removed and all good metal left intact. Where the evapo-rust encounters rubber, it appears to leave it re-conditioned! Smooth and supple afterward.

Hadn't heard of Wurth undercoat yet. I've gone with the Waxoyl Hardwax Underbody, as the Yukon will this spring after a cleaning. Available in rattle-cans & bulk cans. Applies wet and thick, almost foamed, then drys over a few days, skinning down as it does so. Sticky to the touch for weeks. Very little is needed. Using more appears unnecessary, as the normal coats appear to protect as well as the thick. I say appear as I'm only in the fourth year from my first application of it, but so far no rust anywhere it was applied. Even on rust, although not tested on scale (removed scale first). Since that first year using the Waxoyl, I've got to treating anything I have to leave with rust on it (daily driver) with the Penetrol, then a Hardwax topcoat. Great thing about Hardwax for handling scrapes & stones, or used over old drying undercoating, is that it continues to creep, year after year. First encountered it in an '85 VW Golf brought across the pond from Europe. Couldn't figure out why it wasn't rusting out here. The first sign as to why was little bits of black creeping out of drain holes in the rear hatch: Waxoyl Hard Body. Found out it has the rep of "dripping" little bits in the heat. So I expect that Waxoyl Hardwax is not playa safe.

Waxoyl also has a Rust Inhibitor spray, known in the trade as Softwax, as it's the complementary product to the Hardwax. The softwax is great for inside doors and such, really soaking into seams. Being in a winter salting area, I also use it on nuts & bolts, brake line fittings and such, and on other interior areas, like floor pans and such before putting any underlay or carpeting in. This stays wet/waxy and does not fully dry. It inhibits but does not stop existing rust; for that, use the Penetrol.

Jar Jar Sith Lord.Odd. No bears in the dump. Oh well, lets go across the road & pick blueberries..... but don't harm the red dragon that frequents the area from time to time. He and I have an agreement.

@Canoe, you can get a Taiwanese powder-coating kit for cheap at Harbor Freight Tools. I think I saw it on sale for like $30US at one point. The real issue is surface preparation... Sandblasting requires lots of air, which requires lots of compressor, which requires lots of money and space. Has anyone tried powder-coating with a surface preparation other than sandblasting?

I am thrilled to have found this thread. Besides my Wee Beastie ( my 89 camper van I bring to the playa) which needs rust treatment, I have a wedgewood propane gas heater which has rusted from cat spray, and I was literally thinking of how to fix it while drifting off to a nap. I woke up and started reading this thread.

Since most of you seem to be auto restorers, I was wondering if you could recommend a paint which would withstand the heat and not aphyxiate us or poison us by using the heater (being as this is one of two such heaters as the sole source of home heat)? Stove paint? Engine paint?

The good stuff will usually only be sold by the gallon, possibly smaller, at industrial supply houses.I had trouble getting even the cold galvanizing at home depot, but it showed up eventually.Always available at a supply house.

Look for a good heating supply place too.If you can't find one, we have one here I can refer you too.High temp wire by the foot, impossible to get ceramic burners etc.Special adhesive for ceramics.

Spray paint is always lower temp than the high temp stuff.They make a low range in color to about 500 degrees.The better silicone is good to 1200 degrees.Usually only silver, maybe black.